Arc blowing chimneys for circuit breakers having a large breaking capacity



A ril 26, 1960 J. BONNEFOIS ETA ARC BLOWING CHIMNEYS FOR CIRCUIT BREAKERS HAVING A LARGE BREAKING CAPACITY Filed Sept. 4, 1957 3 Sheets-Sheet 1 .727) ZONNEFD/S 7 08: #00427.

r 26, 1960 A J. BONNEFOIS ET AL 2,93 ,629

ARC BLOWING CHIMNEYS FOR CIRCUIT BREAKERS HAVING A LARGE BREAKING CAPACITY Filed Sept. 4, 1957 3 Sheets-Sheet 2 FIG. 3

April 26, 1960 J. BONNEFOIS ET AL 2,934,629

ARC BLOWING camusvs FOR cxacum BREAKERS HAVING A LARGE BREAKING CAPACITY 3 Sheets-Sheet 3 Filed Sept. 4, 1957 k I In! FIG. 8

FIG. 10

FIG. 9

United States Patent ARC BLOWING CHIMNEYS FOR CIRCUIT BREAKERS HAVING A LARGE BREAK- ING CAPACITY Jean Bonnefois, Paris, and Robert Huckel, Saint Quentin, France, assignors to Compagnie Generale dElectricite, Paris, France, a corporation of France Application September 4, 1957, Serial No. 682,051 Claims priority, application France September 10, 1956 11 Claims. (Cl.'200-144) It is known that the use of arc chutes comprising deionization plates of magnetic material separated from one another for the extinguishing of current breaking arcs in circuit breaking equipment is now quite a common feature.

In the case of apparatus having a high break capacity for decreasing the are energy and increasing the efficiency of the cooling of metal surfaces on the hot ionized gases developed by the are, one tries to keep the spacing between the plates as small as possible; the influence of the counter-pressure generated by these same gases then becomes important and is the source of disturbances leading to untimely re-starting of the are.

This has been obviated, heretofore, by a special design of the configuration of the arc chute and arrangement of the magnetic plates which leads to a generally complicated and costly construction.

The present invention obviates this by a simple modification of the structure of the plates, the overall arrangement used for all breaking capacities not being altered substantially.

Its object is a stack of defionization plates for an arc extinguishing arc chute consisting of a series ofmagnetic plates arranged parallel to one another or fanwise, characterized in that the plates are connected electrically in pairs, discontinuously through the stack of plates and in preference laterally with respect to the axis of the arc chute corresponding to the direction of motion of the are inside that are chute.

By such an arrangement, and in case of the interruption of large currents, a sectioning of the arc is effected into a plurality of separate arc sections; the continuous path followed by the current consists of thesev arcsections interconnected by the paths followed by the current in the very thickness of plates and in the electric interconnections of said plates; channels are provided inside the plate pairs for the escape of hot gases from the arc formation, these channels not being traversed by the arc sections during the current breaking process.

Such an arrangement of theplates in the stack may be obtained in many manners, such as following:

One may, for instance, use de-ionization plate pairs consisting, each one of them of a quadrangular sheet of magnetic material which has been bent on itself in the shape of a deep U the bottom of which is imbedded in a groove in the Walls of the arc chute parallel to the general direction of motion of the are; preferably the various Us will be inverted alternately and the spacing between two adjacent Us will be less than the distance between the two branches of one U. More generally,

the successive electric connections between two adjacent coupled plates may be alternately provided on either side of themiddle plane of the stack, so as to ensure the centering of the are by a balancing of the electro-dynamical stresses exerted on the arc sections; also the spacing between two adjacent non-coupled plates may be less than the spacing between twoladjacent coupled plates.

Alternately each pair of plates may consist of two 'ice plane sheets facing eachother, these two sheets being cambered along one of their edges at least, so as to unite them jointingly and electrically on that edge and in the direction of motion of the are. Alternately again, each pair of plates may consist of two plane sheets facing each other and connected with each other by one or more conducting cross braces, offset towards the sheet edges.

To that arrangement, which represents the essential basis of the invention, may be added other special features,.new or known; thus the plates may be notched in a V in the zone of motion of the movable contact of the circuit breaker and of arc formation. In the case in which sheets of magnetic material folded into a U, the bottoms of the Us may be cut at the height of that same zone of arc formation.

Finally, inside the channels for evacuating the hot gases generated by are formation, it may be interesting to reinforce the cooling of said hot gases; to do so, there will be arranged between two coupled plates a metal sheet the good thermal conductivity of which will assist in the accelerated cooling of the gases.

,T he various constructional dispositions which have just been set forth will appear in all their details in the following description, with reference to the appended drawing wherein:

Figure 1 is a view in longitudinal section along the trace ABCD in Figure 2 and in elevation, of an arc chute in a circuit breaker, comprising a de-ionization stack according to the invention and with plates coupled into a U according to Figure 4.

Figure 2 is a view in transverse section and in elevation of the same are chute according to plane EF in Figure 1.

Figure 3 is a partial view in'transverse section and in plan of part of the plates and supporting structure of Figure 1.

- Figure 4 is a view in perspective of an example of two magnetic plates coupled into a U for a de-ionization stack according to the invention.

Figures 5, 7, 9 and 10 are partial views, in plan of an arc chute for are extinguishing for a circuit breaker showing four modified plate stacks according to the invention.

Figures 6 and 8 are views in perspective, of two magnetic plates coupled respectively according to Figures 5 and 7.

The pair of plates represented in Figure 4 is constituted 1 by a rectangular sheet of magnetic material which has been bent into a U along lines ef and gh. In addition, the ecbg portion has been cut away, line cb being substantially at mid height of the plate; two V-shaped notches 10 and 11 have also been cut away so as to face each other on the lower edge of the two branches of the U and in the middle thereof. The entire outer surface of the U located above the line abcd, i.e. approximately the upper half of that surface is coated with an are resistant insulating material.

In a general manner and whatever may be their particular embodiment, the plates may be coupled electrically only in the zone of about that one half of the plates opposite the arc formation zone; in that latter zone each of plates may be notched substantially along a V so as to provide a channel for the displacement of the movable contact or spark extinguisher.

What characterizes essentially the arc chute represented in Figures 1 to 3 is that it includes a de-ionization stack constituted by a series of coupled'plates 12 according to Figure 4. As shown especially in Figures 1 and}, the Us are so arranged as to be inverted successively with respect to one another and the advantage of that inverted mounting will be indicated later.

The are chute itself is formed of two parallel panels V 13 and 14 of insulating material resistant to high tem- 3 peratures, these two panels being united at their ends by two walls 15 and 16 having a U-shaped section, of the same insulating material. The panels and walls are secured together either by means of screws and nuts 17 or by. rivets.

Inside the arc chute and parallel to the panels 13 and 14 are mounted two plates 18 and 19 (Figure I) of an are resistant insulating material so as to provide the constricted channel for are formation.

At the upper level of that channel are secured two supports 20 and 21 and two other supports 22 and 23 of a material resistant to high temperatures are also secured by screws and nuts on the panels 13 and 14 in the higher portion of the arc-cutting chamber, The four supports allow a simple and economical positioning and fastening of the U-shaped plates 12 of magnetic material.

The are tips and movable contacts are so arranged that during the operation of the circuit breaker they move relatively inside the channel formed by the lined-up notches 10 and 11 of the plates 12 of magnetic material.

Finally the arc chute is closed, at its upper portion, by a flame protecting screen 24.

The operating procedure of the equipment just described when an arc is extinguished is as follows:

In the case of weak currents, that is those With negligible self blowing effect, the constricted channel for are formation and for the displacement of the movable contact allows the cooling of the ionized gases on the walls of said channel and results in an-easy cutting-off of these currents.

Similarly the cutting off of medium currents in the V-shaped notches zone is carried out without any difficulty, the important spacings inside the plates 12 (U-shaped) allowing the hot gases to come out at the top and cool off and extinguishing takes place.

It is particularly in the case of large currents i.e. shortcircuit currents extinction that the advantage of the invention appears,

The spaces inside the Us of the magnetic-plates leave a free passage for the ionized gases which form immediately after the starting of the arc and rise in the arc chute; the inner surface of plates 12 cools these gases when they go through. As to the are, by rising under the. action of the electro-dynamic and electro-rnagnetic forces, it reaches the bottoms of the notches 10 and 11 and enters the de-ionization stack where it is sectioned into arc fragments developing between the plates 12 these arcs being connected by the flow of current inside the very mass of the Us.

In Figure 3, there has been shown in solid lines the arc sections and in dotted lines the current flowing through the mass of the Us and connecting the arc sections; due to the inversion of the Us there is a balancing of the electro-dynarnical stresses exerted on the arc sections, which makes it possible to center the arc in the arc chute.

At the level of the abcd planes, these arcs stop since they encounter the insulating coating and are extinguished at the first passing of the current through zero. No disturbance is to be feared under the action of the counter! pressure of the ionized gases since the latterrise inside the Us, while arc sections are fixed between the Us.

It will be convenient, therefore, to have a spacing between adjacent Us relatively small with respect to the aperture of the Us so as to decrease the available are energy and facilitate the flowing of gases; thus the width of aperture of the Us may reach two to three times the widthof th e spacing between two adjacent Us.

The screening 24 located at the upper portion of the arc chute aims to reduce largely the outer manifestations which might be feared by a sudden escaping of the ionized gases and thus to decrease the safety distance to be provided above the cutting-off chamber.

The are chuterepresented in Figure consists of two shells 30, assembled by two lines of joint 31. The large opposite walls of that are chute comprise grooves 32 for the positioning of the plates.

It has been assumed that each pair of de-ionization plates consisted of two plane sheets 41 cambered at their edges at 42 so as to touch all along these edges at 43 thus setting up an electrical contact. Each sheet offers the shape of a wide and shallow gutter, Such a pair of plates is represented in perspective in Figure 6 and the upper and outer portion of the plates is coated with an insulating, arc-resistant material; the two sheets 41 also comprise, at their lower portion, a V-shaped recess for the passing of the movable contact of the circuit breaker.

Many modifications to this arrangement may be imagined within the scope of the invention: camber angle more or less close to one of the sheets 41 may be plane with no camber from one to the other end; one of the sheets or both are cambered only along one edge which gives each plate substantially the shape of a U with a fastening tail-piece in the groove of the arc chute.

In the chimney represented in Figure 7 the grooves 32 of the walls have been widened so as to allow the placing in position of double de-ionization plates each one consisting of two plane parallel sheets 44, spaced by conducting cross-braces 45; these cross-braces are offset with respect to the longitudinal middle plane of the are chute.

These cross-braces may extend all over the heights of the plates or a portion thereof only, or they may consist of a series of little bars spaced all along the height of the plates. These cross-braces may also be located all on one and the same side of the longitudinal middle plane of the arc chute, or they may be on both sides of that plane when passing. from one plate to the next. As for the plates, they may be secured in a single groove, all the grooves being either on one wall of the arc chute or alternately on one or the other wall when passing from one plate to the next.

Figure 8 shows a view, in perspective, of such an example of cross-braced double plates comprising the same minor features as in Figure 6. i In case the depth of the arc chute leads to too large values of the thicknesses of the gas evacuation spaces, and in order to preserve for these zones a sufficient efiiciency for gas cooling one may, according to the invention, place additional coolers inside these spaces.

, Thus, asshown in Figure 9, a cooling plate 46 may be inserted between the two cambered sheets 41 of Figure 5. One may also, and as represented in Figure 10, start from a sheet which is bent twice'parallel to itself so as to constitute, on the one hand, a de-ionization plate and inside it a cooling sheet 47.

The present invention also covers the arc extinguishing arc chutes ,for circuit breakers comprising plate stacks such as those described above.

We claim:

.1. A device'for extinguishing an are moving in a determined direction inside of an arch chute comprising three sections in said direction of displacement of the are, a section where the arc is formed and in which relatively movablecontacts with the are tips are located, asection. wherethe arc is extinguished and a section where the gases are evacuated, provided with a stack of de-ionization plates oriented in a direction substantially perpendicular to the path of the arc, said stackbeing located in the section of arc formation and the section ofarc extinction, said plates being connected electrically in pairs in such manner that adjacent pairs are not interconnected, the connections appearing in the arc extinction section, laterally relative to the middle plane of the chute which parallels the arc path, said plates and their connections being arranged in such manner as to'create inside each said pair of plates, and all along the width and height thereof, a passage for evacuating gases, two such adjacent passages being separated by a channel provided between plates of the two corresponding pairs all along the width and height of the plates, inside of which channel an arc section moves resulting from the sectioning of the main are.

2. A device for extinguishing an arc according to claim 1 characterized in that each pair of de-ionization plates is constituted by a quadrangular sheet of magnetic material bent on itself in the shape of a deep U, the curvature forming the bottom of the U being directed in the direction of the displacement of the arc and extending along at least the entire arc extinction section and the two sides of the U constituting two adjacent plates of the stack.

3. A device for extinguishing an arc according to claim 2 characterized in that the Us are inverted alternately with respect to the middle plane of the stack of plates.

4. A device for extinguishing an arc according to claim 1, characterized in that each pair of de-ionization plates is constituted by two adjacent plates, at least one of said plates of each pair being cambered on at least one of its edges in the direction of displacement of the arc so as to be connected jointingly and electrically therealong to the other plate of said pair.

5. A device for extinguishing an arc according to claim 1, characterized in that each pair of de-ionization plates is constituted by two adjacent plates connected with each other by at least one electrically conducting cross brace offset relative the path of displacement of the arc towards the edges of the plates in the arc extinction section.

6. A device for extinguishing an arc according to claim 1, characterized in that the successive electrical connections in said stack are arranged alternately on opposite sides of the middle plane of the stack of plates.

7. A device for extinguishing an arc according to claim 1, characterized in that the spacing between two adjacent electrically connected plates is greater than the spacing between two adjacent non-connected plates.

8. A device for extinguishing an arc according to claim 1, characterized in that each pair of plates is coated with an are heat resistant insulating material only on the sides of the channels crossed by the are sections and in a zone of about half of each plate in the section where the gases are evacuated in the chute.

9. A device for extinguishing an arc according to claim 1, characterized in that in the passage between two electrically connected plates there is provided a metal sheet in the direction of displacement of the arc for accelerating the cooling of hot gases evacuated through the passage comprised between said plates.

10. A device for extinguishing an arc according to claim 1, characterized in that two are resistant insulating plates are provided defining a constricted channel within which the contacts move relative to each other, said plates being parallel and located inside the chute in the zone of arc formation.

11. A device for extinguishing an arc according to claim 10, characterized in that the plates of the stack are, in the zone of arc formation, notched substantially so as to provide an extension of said constricted channel inside of which the relatively movable contacts are located.

References Cited in the file of this patent UNITED STATES PATENTS 1,840,292 Slepian Jan. 5, 1932 1,888,707 Todd Nov. 22, 1932 1,963,643 Brainard et al. June 19, 1934 1,966,316 Slepian July 10, 1934 2,353,729 Jensen July 18, 1944 2,596,865 Peter May 13, 1952 2,632,074 Herman Mar. 17, 1953 2,639,353 Jansson May 19, 1953 2,734,970 Spears Feb. 14, 1956 FOREIGN PATENTS 618,749 Great Britain Feb. 25, 1949 846,872 France June 19, 1939 

